I got a 2005 Dodge Durango with 120,000 miles 3.7L engine . I thinking of doing a tune up changing the spark plug . My question is what spark plug is best for this engine Champion ? Another question why when I remove the transmission oil dipstick is very hard to put it back with out putting up with a fight ? I new to this Durango any information will help thank ..

Engine oil Dipstick have a really dark brown stain is this normal ? thank

 

I would use Champion.

https://www.sparkplugs.com/Automotive-l134.aspx

 

They don't offer Champion for my engine.

 

My fault, I read it as 4.7 liter.